The present invention relates to a system of producing methanol.
The most recent technique for methanol synthesis involves a low pressure process by which synthesis gas is prepared. This synthesis gas is prepared by the steam reforming or partial oxidation of a liquid or gaseous hydrocarbon feedstock or by direct combination of carbon dioxide with purified hydrogen rich gases. Typically, naphtha or natural gas feedstock is desulfurized, preheated, mixed with a superheated steam and then reacted over a conventional catalyst in a multi-tubular reformer. After cooling, the synthesis gas is compressed to the required synthesis pressure. The synthesis gas is passed into a hot-wall convertor over a low pressure methanol synthesis catalyst at a temperature range of 250.degree. to 270.degree. C. The crude methanol thus formed is condensed and separated from the uncondensed gases which are recycled with makeup synthesis gas and fed back to the converter. See, for example, page 733 of the "Chemical and Process Technology Encyclopedia".
In the aforementioned process and in other processes of producing methanol by techniques known today, it is necessary to provide production facilities where a large amount of hydrogen and carbon monoxide are produced by environmentally dangerous processes, by methane cracking and coking. These facilities are environmentally limited to certain heavy industrial areas of the world and necessitate long-range and expensive transport of the finished methanol. The transportation expense offsets the economic production of methanol in the volume heretofore contemplated.
Merthanol, wood alcohol, has been and still is a key chemical used in the production of many industrial and consumer products and is now being sought after as a fuel. Thus, as petroleum products become less available and more expensive, the Government and consumers are seeking ways and techniques for reducing existing fuel shortages and the cost of new fuels. For example, see "Gasohol, A Technical Memorandum", September 1979; Congress of the United States, Office of Technology Assessment (OTA), Washington, D.C. 20510, page 60. In the introduction, this Memorandun states "In fiscal year 1979, OTA estimated that federal expenditures of between $13 and $17 million directly supported the development of alcohol fuels from biomass. In fiscal year 1980 the Administration's research activities are expected to be funded at a level between $18 and $25 million. Additional subsidies include $40 million in loan guarantees, exemption of the federal excise tax on gasohol (for domestic production and imports), eligibility of alcohol fuels for entitlement awards and an investment tax credit of 20% on alcohol fuels facilities." The most promising fuel to alleviate current and anticipated shortages is methanol. Methanol is produced from carbon feedstocks such as natural gas (methane) and coal which are in plentiful supply and are not dependent on grain as is ethanol. Methanol can be mixed with gasoline to form gasohol or even used independently as a fuel. Methanol, as a fuel, has a research octane rating of 106-115 and a motor octane rating of 88-92. When 9 parts gasoline are mixed with 1 part methanol, the research octane rating of the mix is increased from 91.1 to 95.5 octane, and the motor octane rating from 82.5 to 84.5 octane. See, for example, pages 4-45, "Energy Technology Handbook", Douglas M. Considine, McGraw-Hill, Inc.
Methanol is also a competitive way of tranporting natural gas from the wellhead to the consumer. Wellhead gas, which is currently being burned off into the atmosphere in many major oil fields outside the United States, is a potentially cheap fuel when converted to methanol and shipped to the marketplace. Other natural gas producing fields that are not accessible to gas pipelines are compressing the gas to liquid natural gas (LNG) and shipping the compressed gas to gasification plants that have access to gas pipelines. The conversion and shipping of methanol to gasification plants is a simpler, safer and more economical way of transporting natural gas. See pages 2-124, "Energy Technology Handbook", Douglas M. Considine, copyrighted 1977, McGraw-Hill, Inc.
It therefore is an object of this invention to provide a method and apparatus for producing methanol by environmentally acceptable techniques.
It is another object of this invention to provide a method and apparatus for producing efficiently and economically both small and large quantities of methanol.
It is another object of this invention to provide a method and apparatus for producing methanol to be used as a fuel or fuel additive from pipeline or wellhead natural gas.
It is another object of this invention to provide a method and apparatus for producing methanol as a transport medium of natural gas from a wellhead to gasification plant.